My fan clutch went out on my '96 at about 110k... I don't THINK it's the sort of thing that's really important to replace preemptively, though- a simple check will test function, and they're easy enough to replace on the fly- I did mine in the street on my lunch break.

I replaced two water pumps in my '85 in 250,000 miles... since these suck, and can't conveniently be replaced on the side of the road, it might not be a bad idea to do it preemptively... but it's been my experience that you get some warning that it's going out- your belt will start squealing or you'll get small leaks before it blows completely.

My '96 recently started smelling like coolant, so I'm expecting to replace my water pump now in this one, too.